At present, various mechanisms and systems are utilized for locking a seat belt retractor. Specifically, mechanisms are employed with the seat belt retractor so that when a vehicle employing the seat belt retractor undergoes a predetermined acceleration or deceleration, an inertia member senses this vehicular acceleration change and shifts from a rest position, thereby precipitating the locking of the seat belt retractor. As used hereinbelow, acceleration and deceleration are used interchangeably to denote a change in velocity of a vehicle. Often, the inertia member when shifted operates a lock member such as a lever or pawl member which locks into a geared or toothed wheel that can be fixed to a spool around which the seat belt or seat belt webbing is wound. When the inertia member is shifted, the lock member locks into the wheel, and the spool is unable to rotate in at least the belt protraction direction that would be required for seat belt webbing to be protracted or pulled out from the seat belt retractor.
When a vehicle experiences a rapid deceleration, all items within or connected to the vehicle that are not fixed or secured will have an inertial tendency to continue forward. For example, items in an empty seat or in a cargo area of a vehicle will often slide forward from a rest position when the vehicle rapidly slows.
Another example is a seat that is in an unlocked position. Many vehicle seats are designed to be folded down, or manually released, for quickly and easily moving the seat in order to gain access more easily to an area adjacent to the seat. For instance, a two-door vehicle may have a back seat which is substantially accessible for a passenger's body only by releasing a front seat so that the passenger may ingress the vehicle. In some vehicles such as station wagons, a rear row of seats is provided which may fold down or only a single seat in the row such as the middle seat may pivot so the area they or it occupies may be used as cargo area. In other vehicles, a seats or seats are provided which may fold down to provide access from the interior of the vehicle to a trunk or storage compartment. If retractors are located in these pivotal seat backs, then the seat backs need to be in their upright locked position during vehicle operation for proper inertia sensor operation.
When the seat back is not latched and the vehicle is operated, then the inertia sensor will not operate properly to cause retractor locking at excessive decelerations since the seat back is no longer locked against movement due to its own inertia in these conditions. Accordingly, if a pivotal seat is not secured, the inertia sensor will move with the seat back and thus will not operate to cause retractor locking.
Prior retractors that locked when the seat back in which they are mounted is not secured are carefully constructed to avoid shifting the inertia member, and instead focus on shifting the levers or pawls of the locking mechanism that the inertia member operates during excessive vehicle accelerations/decelerations. To this end, prior retractors have required modifications to the inertia member lock mechanism and have also needed precision design of their components to properly activate the locking mechanism, see U.S. Pat. Nos. 6,045,194 and 6,302,489.
Accordingly, there is a need for a retractor interlock system that is better suited for use with known retractors. More specifically, an interlock system that does not require significant alterations to the inertia locking system would be desired.